innovating and adopting new methods to facilitate tilapia cultivation (Abraham et al., 2013).
One such innovation used by some fishermen and entrepreneurs is tilapia cultivation using the
pond liner method (biofloc) (Rochaeni & Humaerah, n.d.).
Biofloc Technology (BFT) has several advantages, including the ability to cultivate fish
with minimal water and land requirements, and sometimes without changing water, as well as
high feed efficiency (Avnimelech, 2009). In this technology, the waste from feed and fish
excretion, which would normally become pollution, is converted into feed for fish growth,
reducing the amount of feed required. The balance between beneficial bacteria, feed, carbon
supply, and strong aeration maintains good water quality. The floccules composed of various
organic materials, plankton, and bacteria can be used as feed for fish (Emerenciano et al., 2013).
In the North Sulawesi Province, specifically in the Matungkas Village, North Minahasa,
there is an entrepreneur who specializes in freshwater fish farming, particularly tilapia, using
the pond liner method. This method is still uncommon in North Minahasa Regency. The owner,
Mr. Ronny Lensun, has been running this business for approximately three years. The
marketing process is conducted directly from the cultivation site.
After an initial observation, the issue identified by the author is that the income
calculation for this business, undertaken by the owner, still uses a simple method, such as
calculating income and expenses. With a proper income analysis, a business can clearly
understand the production and selling prices, which significantly impact the entrepreneur's
income (Irwandi et al., 2015).
Based on the above background, the author aims to analyze the income of tilapia fish
farming using the pond liner method (biofloc) in Matungkas Village, Dimembe Subdistrict,
North Minahasa Regency. The research objectives are to gain a clear and detailed
understanding of tilapia fish farming using the pond liner method.
Literature Review
1. Pond Liner Method (Biofloc)
According to Suprapto and Samtafsir (2013:17), biofloc comes from the words "bios,"
meaning life, and "floc," meaning clump. Biofloc refers to a collection of various organisms
(bacteria, fungi, algae, protozoa, worms, etc.) that are grouped together in clumps. This
technology initially adopted the principles of biological waste treatment (activated sludge)
involving microorganism activities, such as bacteria.
Organic matter is stirred and aerated. Suspended organic matter is broken down by
aerobic heterotrophic bacteria into inorganic compounds. If organic matter settles without
stirring, anaerobic conditions occur, stimulating anaerobic bacteria to break down organic
matter into simpler organic substances and toxic compounds such as ammonia, nitrite, H2S,
and methane. Sedimented waste must be removed promptly to prevent problems (Rahman,
2018).
In the biofloc technology concept, inorganic nitrogen compounds, especially toxic
ammonia, are recycled into microbial cell protein that can be consumed by detritus-eating
organisms such as tilapia, shrimp, vaname shrimp, catfish, and tilapia. The process involves
stirring and aerating organic matter in the pond to dissolve it in the water, promoting the
development of aerobic heterotrophic bacteria on organic particles. These bacteria break down
organic matter, absorb minerals such as ammonia, phosphate, and other nutrients in the water.
As a result, water quality improves, and organic matter is recycled into enriched detritus
(Suprapto & Samtafsir, 2013).
According to Suprapto and Samtafsir (2013:19-20), the functions of biofloc in the pond
include: